Molecules can exist in a wide range of astrophysical environments, from the extremely cold
regions between stars to the atmospheres of stars themselves.

To date, nearly 200 molecular species have been tentatively or definitively identified in
interstellar or circumstellar clouds, while about 50 have been identified in studies of comets in our solar system.
Numerous isotopologues of interstellar and circumstellar molecules have
also been observed.

Some detections reported on these pages may be controversial, but
all are taken from the peer-reviewed astronomical literature. A questionable
identification may be removed at a later date if circumstances warrant.

Jacque Crovisier has amassed a comprehensive
compilation
of species observed to date in the interstellar medium, in comets, or in
non-terrestrial planetary atmospheres, plus additional ones which may prove
to be found.